Manufacture of exceedingly-thin metallic glowing filaments for electric incandescent lamps.



UNITED STATES r ANTON LEDEREB, OF ATZGERSDORF, NEAR VIENNA, AUSTRIA-HUNGARY.

MANUFACTURE OF EXCEEDINGLY-THIN INIETALLIC GLOWING FILAMENTS FOR ELECTRIC INCANDESCENT LAMPS.

No Drawing.

T 0 (IN -u-lzom -z't may-rom-ern lie it known that I, An'rox LEDERER, a

subject of the Empire of Austria-Hungary,

of which the following is a specification.

My invention relates to improvements in the manufacture of metallic glowing filaments for electric incandescent lamps and has for its object the production of exceedingly thin filaments from comparatively thick raw filaments, obtained by forcin the material under treatment through a die of a comparatively large diameter.

lVith economical burning electric incandescent lamps having metallic glowing filaments and being designated for higher tensions and less illuminating power as for example for 110 volts and 10 candles power, the diameter of the filamentneed notbe greater than some thousandths of a millimeter- Most of the metallic glowing filaments are produced by forcing pastes through suitable dies; now it is very ditiicult from the technical point of view to make dies having a diameter of about 0.005 to 0.008 of a millimeter and consequently the manufacture of 'metallic glowing filaments of such small diameters is nearly impossible.

The process according to this invention allows of the manufacture of filaments even of the small diameters as above indicated and of all metals and metal alloys; I will describe the same as applied to the manufacture of filaments of tungsten or of molybdenum.

Finely powdered metallic tungsten is intimately mixed with also finely powdered oxid of zinc or with sulfid of zinc and with an organic agglutinant in such a quantity that the finished filament does not contain any carbon. From this mixture a paste 1s made by grinding. The paste is then forced through a die in order to obtain filaments which are heated under exclusion of air. Care is to be taken that temperature be not raised too high because in this case the added substance might easily be volatilized.

The filaments thus obtained are glowed in an inert atmosphere or in vacuo by the Patented Aug. 20, 1912.

Application filed April 3, 1906. Serial No. 309,716.

electric current passed therethrough, whereby the oxid of zinc or the sulfid of zinc combines with the carbon of the agglutinant and is volatilizcd partly as carbonic oxid or as carbonic acid and partly as sulfuret of carbon and as a metallic zinc. The filament which originally was of a greater volume visibly shrinks and sinters.

I found that raw filaments 'of a diameter of 0.1 mm. beforetreatment have shown a diameter of only 0.01 mm. after having been submitted to the process above described.

It is obvious, that not only the oxid of zinc but also the oxid of cadmium and other easily reducible oxids or sulfids of other volatile metals may be used in this process.

Reduction takes place about according to the formula below:

A further modification of the process consists in preparing filaments of a paste composed of a metallic oxid and of oxid of zinc or of cadmium or of a sulfid of a metal; the following equations show the process:

The quantities of the added substance may be varied within the largest limits without influencing with in any Way the quality of the final product.

It is obvious that filaments of alloys of several other refractory metals may be 100 manufactured in the same way.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The process of manufacturing exceedingly. thin filaments of refractory metal for 105 electric incandescent lamps, which consists in forming a paste composed of the metal in a finely divided condition and an easily reducible and readily volatilizable metallic compound and a suitable agglutinant, form- 110 ing relatively large filaments from the paste thus obtained and glowing these filaments in the absence of oxygen other than that contained in the paste by an electric current,

manufacturing exceed the content of the paste except the metal designed to form the filament.

3. The process of forming filaments for incandescentelectric lamps, which consists V in heating in an inert atmosphere a mixture of tungsten, a readily Volatilizable metal and carbon in the presence of suflicient oxygen combined in the paste to oxidize all the carbon, and by such heating oxidizing the carbon, driving off the resultant gas and volatilizing the volatilizable metal.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ANTON LEDERER.

Witnesses Jonas): Lox, ALVESTO S. HOGUE. 

